Method for degreasing



Jan. 4, 1.938. F. F. RUTHVEN METHOD FOR .DEGREAS ING Filed May-4, 1 9552 Sheets-Sheet 1 AIINVE-NTIORY.

. EZJWI'IKFIIMSfiZIIWII ATTQRNEYS Jan. 4, 1938. F; F RQTHVEN 2,104,102

METHOD FOR DEGREASING Filed May 4, 1935 2 Sheets-Sheet 2 n lmlllh MINIammirww n A I 9 Lu & I A

Patented Jan. 4, 1938 I METHOD FOR DEGREASING Frederick Francis Ruthven,Toronto, Ontario, Ganada, assignor, by mesne assignments, to AluminiumLaboratories Limited. Montreal, Quebec, Canada, a corporation of Canada7 Application May 4, 1935, Serial No. 19,869

Claims. (01. 87-6) This invention relates to method and apparatus fordegreasing articles and various goods such as have become soiledin'their manufacture, and require cleaning prior to further processingas 5 for plating, galvanizing, lacquering, brass-finishto accomplishdegreasing as rapidly and as eco- 6 ing, and for all other treatmentsfor which the nomically as possible. My invention contemsurface ofarticles must be free from grease, oils, plates applying heat to thearticle being treated, waxes, resins, and foreign accumulation adheringeither prior or subsequent to its immersion in the to such articlesbecause of the presence of such cleaning solvent, at such a rate and insuch quanmaterials. Solvents of the kind suitable -for de-- tity thatthe article will attain a temperature of 1 0 greasing includetrichlorethylene, ethylene diat least the vapor temperature ofthesolvent chloride, carbon tetrachloride, tetrachlorethylene after thearticle leaves the bath of boiling solvent and mixtures thereof, andother substances se-. so that the article is devoid of a film of solventlectable in accordance with the properties of the as well as of greasymaterial when it leaves the articles to be cleaned and the character ofthe vapor atmosphere. materials to be dissolved, and in keeping withWhile the. apparatus illustrated may be adaptcommon practice I shallrefer to the results 010- ed to convey baskets of individual articlesthrough tainable by the methods of the present invention the degreasingprocess, in its present form it is n as degreasing irrespective of theparticular classiparticularly suited for the rapid degreasing offication of the materials removed so long as they metallic sheetmaterial. are soluble in the kinds of solvents which are .In its mainfeatures it consists of a tank or usable in commercial practice forcleaning purcontainer 9 which is provided with a heating coil poses, asfor example, the solvents referredto IIJ near its bottom for heating thesolvent H. hereinabove. With this understanding, my in- A coil of sheetmaterial to be cleaned is mounted ventionrelates more particularly tothe degre'asupon a supply spool or spindle I2 and the sheet ing ofarticles which have sufficient heat capacis guided over the guide roll|3, into the tank ity to maintain a temperature at least as high as andunder bath roll hi, to heated roll l5, idler 16, the vapor temperatureof the solvent for a period and over roll I1 to a rewind drum la. Thesheet of time sufficiently long to enable the withdrawal is advancedover the rolls by the application of of the articles from a vaporatmosphere of the driving power to the rewind drum l8 so that 30solvent, degreased and clean, after having passed the sheet ismaintained under tension as it passes through hot solvent. through theapparatus. A squeegee IS with felt- It is among the objects of theinvention to procovered surfaces may be used for maintaining vide methodand means whereby articles ,may be tautness in the sheet throughout itscourse of 3-3 completely degreased in less elapsed time than travel inthetank. heretofore attainable, and to assure freedom of Bath roll ll'is partly immersed in hot con solvent on the degreased articles.densate contained within a pan it so that the Other and more detailedadvantages and 010- sheet will be thoroughly washed in the hot con=jects will appear more fully in the accompanying densate as it'passesunder the roll. If desired, a

40 description and claims and from the annexed pair of buffer rolls 2!may be provided beyond drawings in which is shown an apparatus emtheexit edge of the pan to remove excess solution. ploying the principleunderlying the present in- The coil It may be heated by passing steamvention and designed. for the degreasing of metherethrough, and the heatgiven up by the coils tallic sheet material. keeps the solvent at thebottom of the tank in In the drawings:- ebullition and causes continuousvaporization. 45

Fig. 1 is a plan of apparatus for degreasing All of the space above theboiling solvent up to, metallic sheet material. coils 22 is filled withsolvent vapor so that heated Fig.2 is a longitudinal section of'theapparoll Iii is immersed in a vapor atmosphere. The ratus, and coolingcoils which are in the upper portion of 50 Fig. 3 is a section on line3-3 of Fig. 2. the tank prevent loss of vapor from the tank. 5o

A common practice. heretofore employed for These cooling coils aremounted around the indegreasing metallic products in course of manusideof the wall of the tank and cold water is facture has been to immersesuch products in a supplied thereto for producing the cooling effectbath of boiling solvent, such as trichlorethylene, desired. The vaporlinein the tank is in the and then in a vapor atmosphere of the solventvicinity of the lower tiers of the cooling coils. 55

v for a sufficient period of time to dry the products. The vapor whichcomes in contact with the cool- For this purpose articles may be handledin bulk ing coils condenses and collects in a gutter 25% in wirecontainers or passed through the solvent just below the coils. Thisgutter is a source of m and vapor mediums on chain conveyors. Thissupply of condensate of pure solvent for the liquid procedure has servedsatisfactorily so long as time was not of the essence, but with limitedspace or for the treatment of articles which require very littlehandling, asf'for example, coiled sheet metal, foil, cable, wire, etc.,it is desirable solvent bath in pan 2!! in which roll l4 depends.

receiving distilled solvent and the greasy or otherwise dirty solvent isoverflown from the pan and is collected in the sump 25 at the bottom ofthe tank from whence it may be manually removed.

when the apparatus is not in operation.

Preferably the outer wall of the tank is in,- sulated as at 26 up to thecooling section of the tank so as to preserve vapor conditions in thevapor bath.; Under ordinary conditions there will be no overflow ofvapor from within the tank but a cover 32 may be used to prevent thewaiting away of vapor by air disturbances on the'outside of the tank.

The roll I5 is heated by any suitable means as by passing steamtherethrough, orby gas or electricity, and the temperature of the rollshould be maintained such as to heat the sheet sufficiently to preventthe condensation of the vapor upon the sheet before it leaves theapparatus. The heat provided by the heated roll produces a condition ofsuperheated vapor in the vicinity of the heated roll. Such; factors asthe specific heat of the material being degreased, the quantity orthickness of the material, the desired rate of' passage of the materialthrough the vapor atmosphere, as well as the vapor temperature of thesolvent shouldbe considered in determining the temperature to which theheated roll must be heated. For degreasing sheet aluminum by the use oftrichlorethylene I have been able to increase the rate of degreasingvery materially with the temperature of the steam in the heated roll' atabout-350 F.

The heated roll is mounted upon bearings 21,

28 which are preferably disposed outside of the tank. The heated rollmay be made of any suitable material and I have obtained satisfactoryresults in degreasing sheet aluminum with an iron roll. Especially whenthe surface of the roll is of a harder material than that of the sheetit should. have a polished surface and be driven. In the of solvent canbe exceeded many times without carrying over any solvent with the sheetbeing cleaned.

While I have disclosed a preferred form of ap- I paratus by which mymethod may be utilized for degreasing sheet material, it is to be notedthat an important feature of my method is in pro-.

viding heat in sufilcient quantity to the article being cleaned toprevent such cooling of the article as to permit condensation on thearticle before it leaves the vapor atmosphere. In additionto thedescribed manner of applying heat, I have obtained satisfactory resultsin cleaning sheet' aluminum by heating it before its'entrance into thetank. For articles other than those which may be wound upon a drum andwhich maybe heated by means of a roller, other provision may be made forheating the articles before entering the degreasing apparatus. Forexample, castings requiring to be degreased prior to plating may Ibepassed through a tunnel furnace which would lipipefl serves to conductthe condensate from the .gutterto the bath. The pan is continually tureof the vapor bath.

impart to them enough heat for them to emerge from the degreasingapparatus at a temperature hotter than the solvent vapor.

f It should be noted that if the sheet or other This will produce aflushing action of liquid and improvedcleaning conditions. Because ofthis it is considered preferable to heat'the sheet or other articleafter it enters the vapor atmosphere' in the degreasing apparatus.

What is claimed is:

- 1. In the method of removing oily or greasymaterial from articles, thesteps comprising subjecting an article to be degreased to the action ofa liquid solvent bath, passing the article from the liquid solvent bathinto a vapor bath of said liquid solvent, heating the article to atemperature above the temperature of said vapor bath while the articleis within said vapor'bath, and removing the article from the vapor bathbefore the temperature of the article drops down to the temperature ofthe vapor bath.

2. In the method of removing oily or. greasy material from articles, thesteps comprising subjecting an article to be degreased to the action ofa vapor bath of a solvent for the material on the article with thearticle at a temperature below the temperature of the vapor bath,heating the article to a temperature above the temperature of the vaporbath before the article leaves the vapor bath, and removing the articlefrom the the article at a temperature below the temperature of the vaporbath, raising the temperature of the article to a'temperature above thetemperature of the surrounding vapor bath by heating the article byconduction while the article is immersed in the vapor bath, and removingthe article from. the vapor bath before the temperature of the articledrops down to the tempera- 4. In the method of removing oily or greasymaterial from a metallic strip, the steps comprising subjecting ametallic strip to be degreased to the action ofa vapor bath derived froma liquid solvent for the greasy material on the metallic strip, heatingthe strip while within said vapor bath to a temperature in excess of thetemperature of the vapor bath, and ridding all trace of solvent filmfromthe strip by removing the strip from said vapor bath while the stripis at a temperature in excess of thetemperature of the vapor bath fromwhich it is being removed.

5. In the method of removing oily or greasy material from articles, the,stepscomprising introducing an article within a vapor bath of a solventfor the material on the article, passing the article through a zonecfvapor superheated with respect to temperature of said bath and containedwithin said vapor bath, maintaining the. articlewithin said superheatedzone to raise the temperature of the arttfeie above that of the vaporbath, and thereafter removing the articie from the vapor bath before thetemperature of the article drops'down to the temperature of the vaporbath.

FREDERICK FRANCIS RUTI-IVEN.

. vapor bath before the temperature .of the article i

